package mblog.base;

import java.util.HashMap;
import java.util.Map;

public class suggie {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
//        map.put("1", null);

        System.out.println("=1="+map.putIfAbsent("1", "2"));
        System.out.println("=2="+map.get("1"));
        System.out.println("=3="+map.put("1", "3"));
        System.out.println("=4="+map.get("1"));
    }
}
